abstract base: all previous tests but one passing; no new tests yet

taggit/managers.py

@@ -2,8 +2,10 @@ from collections import defaultdict
 
 import django
 from django.contrib.contenttypes.models import ContentType
+from django.contrib.contenttypes.generic import GenericForeignKey
 from django.db import models
 from django.db.models.related import RelatedObject
+from django.db.models.fields import FieldDoesNotExist
 from django.db.models.fields.related import ManyToManyRel
 from django.db.models.query_utils import QueryWrapper
 
@@ -12,9 +14,10 @@ from taggit.models import Tag, TaggedItem
 from taggit.utils import require_instance_manager
 
 
+
 class TaggableRel(ManyToManyRel):
-    def __init__(self):
-        self.to = TaggedItem
+    def __init__(self, to):
+        self.to = to
         self.related_name = None
         self.limit_choices_to = {}
         self.symmetrical = True
@@ -23,8 +26,9 @@ class TaggableRel(ManyToManyRel):
 
 
 class TaggableManager(object):
-    def __init__(self, verbose_name="Tags"):
-        self.rel = TaggableRel()
+    def __init__(self, verbose_name="Tags", through=None):
+        self.through = through or TaggedItem
+        self.rel = TaggableRel(to=self.through)
         self.verbose_name = verbose_name
         self.editable = True
         self.unique = False
@@ -35,16 +39,13 @@ class TaggableManager(object):
         self.creation_counter = models.Field.creation_counter
         models.Field.creation_counter += 1
 
-    def __get__(self, instance, type):
-        manager = _TaggableManager()
-        manager.model = type
-        if instance is None:
-            manager.object_id = None
-        elif instance.pk is None:
+    def __get__(self, instance, model):
+        manager = _TaggableManager(through=self.through)
+        manager.model = model
+        if instance is not None and instance.pk is None:
             raise ValueError("%s objects need to have a primary key value "
-                "before you can access their tags." % type.__name__)
-        else:
-            manager.object_id = instance.pk
+                "before you can access their tags." % model.__name__)
+        manager.instance = instance
         return manager
 
     def contribute_to_class(self, cls, name):
@@ -60,9 +61,9 @@ class TaggableManager(object):
         if lookup_type !=  "in":
             raise ValueError("You can't do lookups other than \"in\" on Tags")
         if all(isinstance(v, Tag) for v in value):
-            qs = TaggedItem.objects.filter(tag__in=value)
+            qs = self.through.objects.filter(tag__in=value)
         elif all(isinstance(v, basestring) for v in value):
-            qs = TaggedItem.objects.filter(tag__name__in=value)
+            qs = self.through.objects.filter(tag__name__in=value)
         elif all(isinstance(v, (int, long)) for v in value):
             # This one is really ackward, just don't do it.  The ORM does it
             # for deletes, but no one else gets to.
@@ -92,53 +93,48 @@ class TaggableManager(object):
 
     def value_from_object(self, instance):
         if instance.pk:
-            return TaggedItem.objects.filter(
-                object_id=instance.pk,
-                content_type=ContentType.objects.get_for_model(instance)
-            )
-        return TaggedItem.objects.none()
+            return self.through.objects.filter(**self.through.lookup_kwargs(instance))
+        return self.through.objects.none()
 
     def related_query_name(self):
         return None
 
     def m2m_reverse_name(self):
-        return "id"
+        try:
+            return self.through._meta.get_field('content_object').rel.to._meta.pk.column
+        except FieldDoesNotExist:
+            return "id"
 
     def m2m_column_name(self):
-        return "object_id"
+        try:
+            return self.through._meta.get_field('content_object').column
+        except FieldDoesNotExist :
+            return self.through._meta.virtual_fields[0].fk_field
 
     def db_type(self, connection=None):
         return None
 
     def m2m_db_table(self):
-        return self.rel.to._meta.db_table
-
-    def extra_filters(self, pieces, pos, negate):
-        if negate:
-            return []
-        prefix = "__".join(pieces[:pos+1])
-        cts = map(ContentType.objects.get_for_model, _get_subclasses(self.model))
-        if len(cts) == 1:
-            return [("%s__content_type" % prefix, cts[0])]
-        return [("%s__content_type__in" % prefix, cts)]
+        return self.through._meta.db_table
 
 
 class _TaggableManager(models.Manager):
+    def __init__(self, through=None):
+        self.through = through or TaggedItem
+        
     def get_query_set(self):
-        ct = ContentType.objects.get_for_model(self.model)
-        if self.object_id is not None:
-            return Tag.objects.filter(items__object_id=self.object_id,
-                items__content_type=ct)
-        else:
-            return Tag.objects.filter(items__content_type=ct).distinct()
+        return self.through.tags_for(self.model, self.instance)
 
+    def lookup_kwargs(self):
+        return self.through.lookup_kwargs(self.instance)
+    
     @require_instance_manager
     def add(self, *tags):
         for tag in tags:
             if not isinstance(tag, Tag):
                 tag, _ = Tag.objects.get_or_create(name=tag)
-            TaggedItem.objects.get_or_create(object_id=self.object_id,
-                content_type=ContentType.objects.get_for_model(self.model), tag=tag)
+            self.through.objects.get_or_create(**dict(self.lookup_kwargs(),
+                                                      tag=tag))
 
     @require_instance_manager
     def set(self, *tags):
@@ -147,53 +143,43 @@ class _TaggableManager(models.Manager):
 
     @require_instance_manager
     def remove(self, *tags):
-        TaggedItem.objects.filter(object_id=self.object_id,
-            content_type=ContentType.objects.get_for_model(self.model)).filter(
+        self.through.objects.filter(**self.lookup_kwargs()).filter(
             tag__name__in=tags).delete()
 
     @require_instance_manager
     def clear(self):
-        TaggedItem.objects.filter(object_id=self.object_id,
-            content_type=ContentType.objects.get_for_model(self.model)).delete()
+        self.through.objects.filter(**self.lookup_kwargs()).delete()
 
     def most_common(self):
         return self.get_query_set().annotate(
-            num_times=models.Count('items')
+            num_times=models.Count(self.through.tag_relname())
         ).order_by('-num_times')
 
     @require_instance_manager
     def similar_objects(self):
-        qs = TaggedItem.objects.values('object_id', 'content_type')
+        qs = self.through.objects.values(*self.lookup_kwargs().keys())
         qs = qs.annotate(n=models.Count('pk'))
-        qs = qs.exclude(
-            object_id=self.object_id,
-            content_type=ContentType.objects.get_for_model(self.model)
-        )
+        qs = qs.exclude(**self.lookup_kwargs())
         qs = qs.filter(tag__in=self.all())
         qs = qs.order_by('-n')
 
-        preload = defaultdict(set)
-        for result in qs:
-            preload[result["content_type"]].add(result["object_id"])
+        if not 'content_object' in self.lookup_kwargs():
+            preload = defaultdict(set)
+            for result in qs:
+                preload[result["content_type"]].add(result["object_id"])
 
-        items = {}
-        for ct, obj_ids in preload.iteritems():
-            ct = ContentType.objects.get_for_id(ct)
-            items[ct.pk] = dict((o.pk, o) for o in
-                ct.model_class()._default_manager.filter(pk__in=obj_ids)
-            )
+            items = {}
+            for ct, obj_ids in preload.iteritems():
+                ct = ContentType.objects.get_for_id(ct)
+                items[ct.pk] = dict((o.pk, o) for o in
+                                    ct.model_class()._default_manager.filter(pk__in=obj_ids))
 
         results = []
         for result in qs:
-            obj = items[result["content_type"]][result["object_id"]]
+            try:
+                obj = result['content_object']
+            except KeyError:
+                obj = items[result["content_type"]][result["object_id"]]
             obj.similar_tags = result["n"]
             results.append(obj)
         return results
-
-def _get_subclasses(model):
-    subclasses = [model]
-    for f in model._meta.get_all_field_names():
-        field = model._meta.get_field_by_name(f)[0]
-        if isinstance(field, RelatedObject) and getattr(field.field.rel, "parent_link", None):
-            subclasses.extend(_get_subclasses(field.model))
-    return subclasses

taggit/models.py

@@ -25,12 +25,47 @@ class Tag(models.Model):
             return super(Tag, self).save(*args, **kwargs)
 
 
-class TaggedItem(models.Model):
+class TaggedItemBase(models.Model):
+    tag = models.ForeignKey(Tag, related_name="%(app_label)s_%(class)s_items")
+
+    def __unicode__(self):
+        return "%s tagged with %s" % (self.content_object, self.tag)
+    
+    class Meta:
+        abstract = True
+
+    @classmethod
+    def tag_relname(cls):
+        return cls._meta.get_field('tag').rel.related_name
+
+    @classmethod
+    def lookup_kwargs(cls, instance):
+        return {'content_object': instance}
+
+    @classmethod
+    def tags_for(cls, model, instance=None):
+        if instance is not None:
+            return Tag.objects.filter(**{'%s__content_object' % cls.tag_relname(): instance})
+        else:
+            return Tag.objects.filter(**{'%s__content_object__isnull' % cls.tag_relname(): False})
+
+
+class TaggedItem(TaggedItemBase):
     object_id = models.IntegerField()
     content_type = models.ForeignKey(ContentType, related_name="tagged_items")
     content_object = GenericForeignKey()
-    
-    tag = models.ForeignKey(Tag, related_name="items")
-    
-    def __unicode__(self):
-        return "%s tagged with %s" % (self.content_object, self.tag)
+
+    @classmethod
+    def lookup_kwargs(cls, instance):
+        return {'object_id': instance.pk,
+                'content_type': ContentType.objects.get_for_model(instance)}
+
+    @classmethod
+    def tags_for(cls, model, instance=None):
+        ct = ContentType.objects.get_for_model(model)
+        if instance is not None:
+            return Tag.objects.filter(**{'%s__object_id' % cls.tag_relname(): instance.pk,
+                                         '%s__content_type' % cls.tag_relname(): ct})
+        else:
+            return Tag.objects.filter(**{'%s__content_type' % cls.tag_relname(): ct}).distinct()
+            

taggit/tests/tests.py

@@ -84,7 +84,7 @@ class LookupByTagTestCase(BaseTaggingTest):
         apple.tags.add("red", "green")
         pear = Food.objects.create(name="pear")
         pear.tags.add("green")
-        
+
         self.assertEqual(list(Food.objects.filter(tags__in=["red"])), [apple])
         self.assertEqual(list(Food.objects.filter(tags__in=["green"])), [apple, pear])
 

taggit/utils.py

@@ -8,7 +8,7 @@ def parse_tags(tags):
 def require_instance_manager(func):
     @wraps(func)
     def inner(self, *args, **kwargs):
-        if self.object_id is None:
+        if self.instance is None:
             raise TypeError("Can't call %s with a non-instance manager" % func.__name__)
         return func(self, *args, **kwargs)
     return inner